Coaxial transmission line switch



June 16, 1953 c. A. HAULMAN ErAL I 4 COAXIAL TRANSMISSION LINE swncnFiled Aug. 21, 1947 2 Sheets-Sheet 1 D. J H l LFERTY,DE6EASED BY EM.GEORGE, zxzcu'rmx June 16, 1953 4 HAULMAN Em. 2,642,495

COAXIAL TRANSMISSION LINE .SWII CH Filed Aug. 21, 1947 2 Sheets-Sheet 2C.A.HAULMAN 0. J. HlLFERTYpEGEASED av E.M. GEORGE, :xscurmx PatentedJune 16, 1953 COAXIAL TRANSMISSION LINE SWITCH Clyde Austin Haulman,Hyattsville, Md., and

Daniel J. Hilferty, deceased, late of Riverdale, Md., by Ethel M George,executrix, Riverdale,

Applica o ug st .21, .19 7, Serial N 6 ,966

(Granted under Ti l ,11. S. Code (1952),

see. 266) 4 Claims.

This application is a continuation of applica= tion Serial No. 580,053,filed February 27, 1945, for Coaxial Transmission LineSwitch.

This invention relates to a switch for direct.- ing energy from acoaxial transmission line into either of two associated similar coaxialtransmission lines.

In transmission systems employing connected transmission lines havingdifferent characteristics a major problem is encountered in maintainingconstant surge impedance of the line throughout the junction between thediiierent transmission lines in order to prevent energy losses due toreflection. The same problem is encountered when connecting transmissionlines having similar characteristics through a switching means.Transmission line switching devices have been provided heretoforeopera-bleto form a connection between one transmission line and eitherof two other transmission lines. However, the prior devices are notconstructed in a manner so that constant surge impedance is maintainedbetween connected lines throughout the switch. In particular, the priordevices do not include means for eliminating the efiect of theunconnected line on the surge impedance of the connected lines, whicheffect inherently exists since the lines are necessarily mounted inclose proximity within the switching device. Moreover, due to theconstruction of the switch actuating mechanism the prior devices includea cavity, which is large with respect to the external cross-sectionaldimensions of the transmission lines, for enclosing such mechanism and:into which :the trans mission lines extend. Compensating means, such asadjustable capacitors, are provided in an attempt to compensate for theabrupt and severe capacity variations between connected lines due to thecavity, however, such compensating means are'not satisfactory inmaintaining constant surge impedance throughout the switch, foreitherposition of operation thereof, especiallywhen the device isemployed for transferring ultra-high :frequency energy.

Accordingly, it is an object of the present invention to provide a novelswitch for connecting a transmissionline to eitherof two-similartransmission lines, having a substantially constant surge impedance.

A further object is to provide ,a novel switch having the foregoingcharacteristics including an inherently low percentage of reflection andassociated energy loss.

. Another obj ect. is: to provide a coaxial transmission line switch inwhich :the capacity per :unit

ngth between inner and outer conductors is maintained substantiallyconstant throughout the SW1; Qh.

Qther objects and features of the present invention will appear morefully hereinafter from consideration of the following detaileddescription in connection with the accompanying drawing-s which discloseone embodiment of the invention. 'It is to be expressly understood,however, thatthe drawings are designed for the purpose of illustrationonly and are not to be construed as a definition of the limits of theinvention, reference for the latter purpose being had to the appendedclaims.

In the drawings, wherein similar reference characters denote similarelements through the several'views:

Fig. 1 is a diagrammatic illustration of the top view of a transmissionline switch constructed in accordance with the principles of the presentinv n ion;

F ,l igl. 2 is aside view of the switch disclosed in Fig. 3 is-a sideview of the'switch disclosed in Fig. -1 with the front cover removedtherefrom;

Fi 4 is a sectional illustration .along the line l.-4 ofFig. 3;

Fig. 5 is a detailed illustration of one of the elements included in thedevice shown in Fig. 3, and

Fig. 6 is .a sectional illustration along the offset section lines 6-16of Fig. 3.

With referencemore particularly to Figs. 1 and 2 of the drawings, atransmission line switch constructedin accordance with the principles ofthe present invention is disclosed therein including a substantiallyrectangular housing It provided with a front cover plate I i Threecoaxial trans" mission lines 12, i3 and M, each including inner andouter conductors, are shown entering the housing til from the left, topand right, respectively, as viewed in-Fig.-2. The transmission linesI12, 13 and 14 may constitute connection members to which ex;tended,coaxial transmission lines are adapted to be j ined. The housing [0 hastabs I 5 securedthereto-for use in mounting the switch 011 a l ppfllt-Asshown in Fig. 3, the inner conductors of the coaxial lines 12 and 14extend into the housing It in axial alignment, and the inner conductor2-! of t -he. coaxial;line 3| 3 extends into the housing H3 ;at rightangles with respect to the inner conductors of1lines L2 and 14. Theextended inner conductors of th coaxial lines i2 and i4terminateiinconductors:20 and '22 respectively, while the innerconductor of the coaxial line is terminates in tubular conductor 23mounted perpendicular thereto in aXial alignment with the conductors 2i!and 22. The outer conductors of the coaxial lines I2, l3 and M terminateat planes 24, 25 and 26 respectively. From planes 24, 25 and 25throughout the interior of the switch the outer conductors of thecoaxial lines areformed by the figuration of the housing [3. As shown,the extended inner conductors 20,.2! and 22 are symmetrically surroundedby cylindrical walls formed in the housing it having diameters equal tothe inner diameters of the outer conductors of coaxial lines 12, i3 andM. Polystyrene disc's Eilare provided for supporting the conductors 2i!and 22.

In order to selectively establish contact between coaxial line 13 andeither of coaxial lines l2 and H! a movable switch member 3! is mountedfor sliding movements inside the tubular conductor 23. The member 3! mayconsist of a short length of chrome-plated steel rod suitably rounded ateach end as shown in Figs. 3 and 4. By reciprocation of the member iii,to the f right or left as viewed in Fig. 3 of the drawings, relative tothe tubular conductor 23, the inner conductor 25 of the line is may beconnected to either the conductor 20 or the conductor 22. The conductors223 and 22 are hollow at the terminated ends thereof for reception ofthe end of the member 3!, and notches 32 are cut axially in theconductors 20, 22 and 23 to form spring fingers normally urged inwardlyto maintain firm electrical and mechanical contact with the slidingmember 3 I An electro-magnetically operated toggle mechanism is providedfor actuating in the switch member 3! in a manner described heretofore.As shown in Figs. 3 through 6, the switch member 3! is actuated in thetubular conductor 23 by a finger 35 constructed of insulating material.The finger 35 extends from a cylindrical rod 33 pivotably mounted by apin 34. The finger 35 has a square cross-section for operativeengagement in square slot 36 provided in the member 3 i. To allow backand forth movement of the finger 35, as the member 3! is actuated, oneside of the tubular conductor 23 is provided with a rectangular slot 40.The rod 33 includes an extension 4| of substantially squarecross-section at the end thereof opposite the finger 35. The extensionll is provided with an open, longitudinal slot 42 for receiving one endof a toggle member 44 pivotably secured to the end of the extension 4!by means of pivot member 43. The toggle member 44 includes a slot 45 atthe other end thereof for pivotably engaging a stationary pin 45 securedto the housing H3. The ends of a plunger 58 positioned transverselythrough the slot 42, are respectively secured to the armatures, notshown, of actuating solenoids i and 52. The plunger 50 includes anintermediate section 53 which comprises a pair of parallel surfaces toallow operation in the slot 2. A pin 54 is positioned to engageanelongated hole 55 in the section 53 and an elongated hole 55 isprovided in the extension M to provide an operating connection betweenthe rod 33 and the plunger 59. Toggle spring 60 is compressed between ashoulder 6! on the toggle member M and a washer $2 bearing against thepin 55 to provide a snap action in the oscillating movement of the rod33 about the pin 3 5 upon energization of the armatures 5:! or 52. Forease of description the mechanism for actuating the switch member 3: isshown in the mid ositi n of operation. It will be obvious that suchposition will never be maintained during operation as the switch due tothe toggle action of the spring 60. The mid-position shown in thedrawings will be attained only momentarily as the mechanism passes fromone extreme position to the other.

As mentioned heretofore, the switch provided by the present invention isconstructed in such a manner as to maintain continuity of the outerconductors of the coaxial lines through the housing I 0. For ease ofmanufacture however, a cavity 63, which accommodates the rod 33 and thefinger 35, may be provided in the housing In as a continuation of theouter conductor of the coaxial line I3. In order to close the openingthus formed, a sleeve 54, having a longitudinal slot 65 for the passageof the finger 35, is inserted in the housing It) to maintain acontinuous cylingirical wall therein between the planes 2t and 6.

In operation, one of the solenoids, for example the solenoid 5!, isenergized, pulling the plunger 50 to the left as viewed in Fig. 3. Suchmovement of the plunger 59 produces clockwise rotation of the rod 33above the pivot 3 and forces the member 3! into engagement with theconductor 22 of the line M. The spring 60 then functions to bias theplunger 50 to the left so that the solenoid 5| may be de-energizedwithout terminating the electrical and mechanical contact between themember 33 and the conductor 22. Similarly, energization of the solenoid52 will cause the line 33 to snap in a counterclockwise direction toestablish an electrical and mechanical-connection between the member 3iand the conductor 29.

It is to be expressly understood that when the member 3| is moved intoengagement with one of the conductors 2a or 22, for example theconductor 20, the right-hand end of the member 3| extends into thetubular conductor 23, and the distance between the common innerconductor 23 and the un-connected inner conductor 22 is maintained equalto the distance between the inner conductors and the outer conductors ofthe coaxial lines. This relationship maintains the capacity per unitlength of the coaxial lines substantially constant so that substantiallyconstant surge impedance is maintained throughout the switch, thusreducing energy losses due to mismatch and reflection.

There is thus provided by the present invention novel switch means forswitching one transmission line to either of two associated transmissionlines, with the novel means so characterized as to maintainsubstantially constant capacity per unit length of lines throughout theswitch, and hence substantially constant surge impedance throughout theswitch, for either position of operation thereof.- Specifically, theforegoing, is accomplished by providing a switch housing havingcylindrical passages therein which function as the outer conductors ofthe transmission lines through the switch, with such passages havingcontinuous surfaces corresponding to the inner surfaces of theouterconductors, and by providing a novel arrangement for forming thedesired connection between the inner conductors of the transmissionlines wherein the inner conductor of the un-connected transmission lineis maintained spaced from the inner conductors of the remainingtransmission lines by a distance equal to the space betweenthe inner'andouter conductors of each of the transmission lines. Furthermore, it isto be expressly understood that the novel switch provided herein may bereadily sealed without effecting operation thereof for ease ofadaptation to such applications as under-water use and for employment inthe vicinity of explosives or other chemical substances.

Although only one embodiment of the present invention has been disclosedand described herein it is to be expressly understood that variouschanges and substitutions may be made therein without departing from thespirit of the invention as well understood by those skilled in the art,for example, two switch units embodying the principles of the presentinvention may be placed side by side producing a double pole, doublethrow transmission line switch, and that one of the solenoids may beremoved and replaced by spring under tension to bias the switch tonormally maintain a connection between two of the three transmissionlines. Reference, therefore, will be had to the appended claims for adefinition of the limits of the invention.

The invention described herein may be manufactured and used by or forthe Government of the United States of America for governmental purposeswithout the payment of any royalties thereon or therefor.

What is claimed is:

1. A switch comprising two coaxial transmission lines having outerconductors joined in a substantially unbroken connection and havinginner conductors terminated in spaced relationship, a third coaxialtransmission line having an outer conductor joining said first two outerconductors and including a hollow inner conductor in spaced relationbetween the termination of said first two inner conductors, a connectorslidable within said hollow inner conductor and movable to contactselectively either of said first two inner conductors, and anon-conducting member operable to actuate said connector.

2. In a transmission line switching device, a housing, two coaxialtransmission lines oppositely positioned in said housing along a commonaxis and having the inner conductors thereof terminated within saidhousing in spaced relationship, a third coaxial transmission linepositioned in said housing with the inner conductor thereof terminatedwithin said housing in spaced relation with the inner conductors of saidtwo lines and perpendicular to said axis, a switch carrying membersecured in perpendicular relationship to the terminated end of the innerconductor of said third line along said axis, a switch member carried bysaid switch carrying member for establishing a connection between theinner conductor of said third line and the inner conductors of ingforming a substantially continuous surface having dimensions equal tothe inner dimensions of the outer conductors of said two and said thirdlines between the outer conductors of said two and said third linesthroughout said housing.

3. A coaxial transmission line switch comprising a housing, threecoaxial transmission lines having inner and outer conductors, said lineshaving their outer conductors joined by the housing and so arranged thattwo of said lines are oppositely disposed on a common axis with thethird line terminated between the ends of said two lines, a movablemember for connecting either of said two lines to said third line, saidmovable member being in the form of a section of inner conductorslidably mounted on the end of the inner conductor of said third line inelectrical contact therewith and constrained to slide transversely ofthe third line along the common axis of the two oppositely disposedconductors, the length of said movable member being substantially equalto the distance between the inner conductors of said two lines minus thedistance between the inner and outer conductors, thereby maintaining thecapacity per unit length of said connected lines substantially constant,and means for actuating said movable member.

4. A switch comprising two coaxial transmission line coupling elementshaving outer conductors joined in a substantially unbroken connectionand having inner conductors terminating in spaced relationship, a thirdcoaxial transmission line coupling element having an outer conductor insubstantially unbroken connection with the two outer conductors andcomprising a hollow inner conductor spaced between said first two innerconductors, a reciprocally movable conductor contained within saidhollow conductor and movable to contact either of said first two innerconductors selectively, and a non-conducting actuating member operableto move said movable conductor.

CLYDE AUSTIN HAULMAN. ETHEL M. GEORGE, Erecutria: of the estate ofDaniel J. Hz'ljerty,

deceased.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 2,235,010 Chaffee Mar. 18, 1941 2,251,997 Goldmann Aug. 12,1941 2,264,124 Schreiner Nov. 25, 1941 2,344,780 Kram Mar. 21, 19442,360,219 Goddard Oct. 10, 1944 2,425,010 Smith Aug. 5, 1947 2,426,186Dow Aug. 26, 1947 2,427,940 Ayres Sept. 23, 1947 2,472,274 Beleskas June7, 1949 2,478,781 Remschmidt Aug. 9, 1949

